Battery powered elevator systems employ a battery as a power source to an elevator machine that imparts motion to the elevator car. A drive unit containing an inverter is typically connected between the battery and the machine. In motoring mode, the inverter converts DC power from the battery to AC drive signals for the machine. In regenerative mode, the inverter converts AC power from the machine to DC power for charging the battery.
In a battery powered elevator system, the battery may experience overloading when in motoring mode or overcharging in regenerative mode. Overloading negatively affects state of charge/usability of the battery as a voltage/power source. Overcharging negatively affects the health of the battery. Overcharging is normally controlled using a dynamic braking resistor, and overloading is normally controlled with profile modifications.